Modelling silicon carbide formation during heating at constant rate

We build a model, at a mesoscopic, nanometric scale, describing the formation of silicon carbide during heating at constant rate followed by holding at a temperature slightly smaller than the eutectic temperature of carbon and silicon. The number of contacts between silicon grains and graphite plates in the initial powder mixture is shown to influence the speed of the reaction during the step associated with the melting of silicon. After dissolution of carbon in liquid silicon, precipitation of silicon carbide is assumed to obey a heterogeneous nucleation mechanism. In agreement with experiments, the simulation results reproduce smaller reaction speeds for larger silicon grains.